My coworkers and I study adult stem cells that live in the bone marrow. Some of these cells give rise to red and white blood cells and are called hematopoietic stem cells (HSCs). Others give rise to bone, cartilage, and fat and are called bone marrow stromal cells (BMSCs). We found that these different populations are connected to each other and can and do regulate each others' function. We observed that BMSCs can reduce inflammation by communicating with other cells of the immune system. This effect depends on the source of the BMSCs and varies from person to person. We are studying the mechanism how this effect is achieved by the BMSCs. Regarding the hematopoietic support role of the BMSCs in the bone marrow we study a variety of anaemia models to mimic events that might occur in the humans. When we lose blood, we become anaemic, because we also lose the blood cells. Certain toxins (sometimes overdoses of medicine) will cause our red blood cells to dissolve in the circulation (it is called hemolysis) and these will need to be replaced very quickly, since they carry the oxygen. Finally, when the bone marrow gets suppressed (for instance following chemotherapy), we also need to make more new cells so that the number of circulating cells could keep up with the demand. We are doing experiments to find out how the supportive BMSCs can help the bone marrow to produce more cells to compensate for blood loss. We have been studying the relationship between cells in the bone marrow, called the bone marrow niche. This is the space where cells interact and regulate each others functions. We studied how the bone marrow environment changes in a disease called mastocytosis, where mast cells are overproduced. We found that in patients with the disease, the BMSCs can't make bone and can't support blood formation, like they do in healthy people. We are trying to find out how these BMSCs are different from healthy ones.